The invention relates generally to components for molding machines and more specifically to a collapsible mold core assembly typically utilized with an injection molding apparatus.
A constant challenge to mold designers has been the creation of mold structures to produce internal passageways or interior features in a molded product. With sand cast products, sand cores and similar one-use structures typically made from recyclable material are formed into a desired configuration. Subsequent to casting, the sand cores are broken down and the sand is removed and reused.
The advent of plastic molding materials and injection molding apparatus dictated a new approach to core removal. With injection molding apparatus, the sand contamination and the relatively slow production rates associated with destructible sand cores was generally unsuitable. Accordingly, collapsible mechanical configurations having high dimensional accuracy and repeatability have been developed. Typically, a structure disposed centrally within the mold receives and locates a plurality of mold segments which are movable into and out of a component molding position.
For example, U.S. Pat. Nos. 4,383,819 to Letica, 4,731,014 to Von Holdt and 4,756,865 also to Von Holdt teach mold configurations wherein both exterior and interior mold segments dissemble to permit removal of the molded part. U.S. Pat. Nos. 4,362,291 to Fuke et al. and 4,832,307 to Watanabe et al. disclose mold configurations wherein both interior and exterior mold segments are constrained to travel along oblique paths.
U.S. Pat. Nos. 4,378,928 to Kopp et al., 4,533,312 to Von Holdt and 4,627,810 also to Von Holdt teach primary interior mold segments extending through a 120.degree. arc and secondary, fractional mold segments. U.S. Pat. No. 4,541,605 to Kubota teaches a similar configuration having four mold segments.
The configuration and attendant operation of the foregoing devices represent a broad spectrum of approaches to the various problems associated with producing molded parts with undercuts and collapsible cores. A review of such patents also reveals that improvements in the art of collapsible core molds to produce an even wider variety of molded parts is both desirable and possible.